Electrode assembly, and lithium ion electric roll using the electrode assembly

ABSTRACT

An electrode assembly and a lithium ion electric roll having the same are provided. The electrode assembly includes: a first electrode unit; a first anti-puncture cushion; in which the first electrode unit includes a first electrode sheet, an second electrode sheet, and a separator, the separator is disposed between the first electrode sheet and the second electrode sheet; the first anti-puncture cushion is disposed on a side of the first electrode unit along a width direction, and covers an edge of the first electrode sheet.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of U.S. patentapplication Ser. No. 15/087,096, entitled “ELECTRODE ASSEMBLY, ANDLITHIUM ION ELECTRIC ROLL USING THE ELECTRODE ASSEMBLY”, filed on Mar.31, 2016, which claims priority to Chinese Patent Application No.201510932557.3, entitled “ELECTRODE ASSEMBLY, AND LITHIUM ION ELECTRICROLL USING THE ELECTRODE ASSEMBLY”, filed on Dec. 14, 2015, which isincorporated herein by reference in its entirety.

TECHNICAL FIELD

The present application relates to the field of energy storage devices,and in particular, relates to an electrode assembly, and a lithium ionelectric roll using the electrode assembly.

BACKGROUND

With the development of science and technology, a variety of electronicproducts emerge and almost become an indispensable part in daily life.With advantages of high energy density, long cycle life, environmentalfriendliness and reproductivity, lithium ion batteries have been widelyused in various electronic products.

Generally, lithium secondary batteries are formed through setting anelectrode assembly and electrolyte in a battery shell, and sealing thebattery shell. Electrode units used in the electrode assembly may becategorized into convolution (winding)-type electrode units, alamination-type electrode unit, and folding-type electrode unitsaccording to their structure.

In the related art, a polypropylene layer of a laminated aluminum filmis generally used to isolate an anode current collector in an anodesheet. Since the requirements of energy density of an electric roll atthe market become higher and higher, a thickness of the polypropylenelayer of the laminated aluminum film, and a thickness of the anodecurrent collector become smaller. In one aspect, an anti-puncturestrength of the thinned polypropylene layer becomes lower. In anotheraspect, since the anode current collector of the lithium ion battery isa copper foil, with the restriction of process conditions in the relatedart, burrs may exist on an end edge of the copper foil, which may causethe case where the burrs on the end edge of the anode puncture aseparator and a laminated aluminum film under extreme conditions.However, in a lamination-type or stacking-type lithium ion electricroll, the edge of the thinned anode current collector will becomesharper, which increases the probability that the polypropylene layer ofthe laminated aluminum film is punctured by the anode current collector.

After the polypropylene layer of the laminated aluminum film ispunctured, which may cause battery leakage, and more seriously, mayresult in that the anode is conducted with the aluminum foil layer viacontact. In this case, an electrochemical reaction may occur and thusthe polypropylene layer of the laminated aluminum film may be subjectedto corrosion, which also causes battery leakage and corrosion.

SUMMARY

The present application provides an electrode assembly, and a lithiumion electric roll using the electrode assembly, which is capable ofeffectively reducing the probability that a packaged laminated aluminumfilm is punctured by a pole sheet.

A first aspect of the present application provides an electrodeassembly, including:

a first electrode unit;

a first anti-puncture cushion;

wherein the first electrode unit comprises a first electrode sheet, ansecond electrode sheet, and a separator, the separator is disposedbetween the first electrode sheet and the second electrode sheet;

the first anti-puncture cushion is disposed on a side of the firstelectrode unit along a width direction, and covers an edge of the firstelectrode sheet.

A second aspect of the present application provides a lithium ionelectric roll, including a laminated aluminum film, and the abovementioned electrode assembly, wherein the electrode assembly is wrappedby the laminated aluminum film.

It shall be appreciated that the above general description and thedetailed description hereinafter are only illustrative but not forlimiting the present application.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an integral structure of a lithium ionbattery according to the present application;

FIG. 2 is a schematic diagram of an exterior structure of an electrodeassembly formed by a single lamination-type electrode unit according tothe present application;

FIG. 3 is a schematic structural diagram of a cross section of FIG. 2;

FIG. 4 is a schematic diagram of an exterior structure of an electrodeassembly formed by a plurality of lamination-type electrode unitsaccording to the present application;

FIG. 5 is a schematic structural diagram of a cross section of FIG. 4;

FIG. 6 is a schematic diagram of an exterior structure of an electrodeassembly formed by a plurality of convolution-type electrode unitsaccording to the present application;

FIG. 7 is a schematic structural diagram of a cross section of FIG. 6;

FIG. 8 is a schematic diagram of an exterior structure of an electrodeassembly of a single folding-type electrode unit according to thepresent application;

FIG. 9 is a schematic diagram of an exterior structure formed by hybridstacking of a plurality of types of electrode units according to thepresent application; and

FIG. 10 is a schematic diagram illustrating partially staggering ofadjacent electrode units along a width direction according to thepresent application.

REFERENCE NUMERALS AND DENOTATIONS THEREOF

-   -   1—Electrode assembly    -   10—Bare electric roll    -   100—Electrode unit    -   100 a—Cathode sheet    -   100 b—Anode sheet    -   100 c—Separator    -   100 d—Rib structure    -   12—Anti-puncture cushion    -   2—Laminated aluminum film

The accompanying drawings herein, which are incorporated into andconstitute a part of the specification, illustrate embodimentsconsistent with the present application, and together with thespecification, serve to explain the principles of the presentapplication.

DETAILED DESCRIPTION

The present application is further described with reference to specificembodiments and accompanying drawings. The terms “front”, “behind”,“left”, “right”, “upper” and “lower” described in the presentapplication are given with reference to the state where a lithium ionelectric roll is disposed in the accompanying drawings.

As illustrated in FIG. 1, a lithium ion electric roll is providedaccording to an embodiment of the present application, wherein thelithium ion electric roll comprises an electrode assembly 1 and alaminated aluminum film 2. As illustrated in FIG. 2, the electrodeassembly 1 comprises a bare electric roll 10 and an anti-puncturecushion 12; wherein the bare electric roll 10 is a main electric energygenerating component of the lithium ion electric roll, and generallycomprises at least one electrode unit 100, each electrode unit 100including a cathode sheet 100 a, an anode sheet 100 b, and a separator100 c; wherein the cathode sheet 100 a is isolated from the anode sheet100 b by the separator 100 c, such that the cathode sheet 100 a and theanode sheet 100 b may be subjected to an electrochemical reaction underthe effect of an electrolyte. The anti-puncture cushion 12 is arrangedon two sides along a width direction of the bare electric roll 10(extending leftward and rightward along the paper surface in FIG. 2),and covers an edge of the anode sheet 100 b. Finally, the electrodeassembly 1 is entirely wrapped by the laminated aluminum film 2 from theouter side. In this case, the anti-puncture cushion 12 may serve as abarrier between the laminated aluminum film 2 and the anode sheet 100 b.With the protection isolation structure, the anode sheet 100 b may beisolated by the anti-puncture cushion 12, and thus fails to be in directcontact with the laminated aluminum film 2, thereby reducing theprobability that the laminated aluminum film 2 is punctured (referringto FIG. 1). The corners on the top and at the bottom of the anode sheet100 b are sharp, and a polypropylene layer of the laminated aluminumfilm 2 may be possibly punctured by the anode sheet 100 b along the topor bottom direction in the case where the anode sheet 100 b along awidth direction is covered by the anti-puncture cushion 12. In thiscase, this embodiment provides a corresponding protection measure to thepolypropylene layer of the laminated aluminum film 2. To be specific, asillustrated in FIGS. 2, 4, and 6, in this embodiment, an edge of theanti-puncture cushion 12 along a top and/or bottom direction of the bareelectric roll 10 exceeds the anode sheet 100 b. In this way, after theelectrode assembly 1 is wrapped by the laminated aluminum film 2, theportion exceeding the anode sheet 100 b of the edge of the anti-puncturecushion 12 can be bent, such that the corners of the anode sheet 100 bare completely wrapped by the anti-puncture cushion 12, therebypreventing polypropylene layer from piercing by the corners.

Considering manufacture difficulty, electric roll capacity and the like,preferably, a plurality of electrode units 100 are simultaneously usedfor the bare electric roll 10, and these electrode units aresequentially arranged in a stacking manner along a thickness direction.To ensure that the anode sheet 100 b in each of the electrode units 100is isolated from the laminated aluminum film 2, the anode sheet 100 b ineach of the electrode units 100 needs to be covered by the anti-puncturecushion 12.

The thicknesses of the electrode units 100 may be different, andmeanwhile, the area vertical to a thickness direction may be adjustedaccording to the capacity of the electric roll, or regional spatialstructure and volume desired for accommodating the electric roll. Forexample, the widths of two adjacent electrode units 100 are different(as illustrated in FIG. 7); or for another example, as illustrated inFIG. 10, the widths of four electrode units 100 are the same, but thethicknesses thereof are different. When the electrode units 100 arearranged in a stacking manner, electrode units 100 in each layerrelative to the lower electrode units 100 are partially staggeredrightward along a width direction. Nevertheless, there is morecomplicated situation, for example, size difference still exists in theplurality of electrode units 100 along a length direction (extending ina direction vertical to the paper surface in FIG. 10); or, the pluralityof electrode units 100 are partially staggered, which is not describedherein any further.

When the above case occurs, a rib structure 100 d is formed on two sidesor on one side along a width direction of the two adjacent electrodeunits 100. Since an edge of the rib structure 100 d projects outwardsand is sharp, the polypropylene layer of the laminated aluminum film 2is easily punctured. In order to cope with this situation, the ribstructure 100 d is clad with the anti-puncture cushion 12 in thisembodiment.

In this embodiment, the electrode unit 100 may employ various types,such as, lamination type, convolution type, a folding type, and thelike. For example, the electrode assembly 1 as illustrated in FIGS. 2and 3 only comprises lamination-type electrode units 100. In theelectrode unit 100, the cathode sheet 100 a, the separator 100 c, andthe anode sheet 100 b are alternately stacked. However, the electrodeassembly 1 as illustrated in FIGS. 4 and 5 comprises threelamination-type electrode units 100 with the lengths and widthssequentially decreasing. For another example, the electrode assembly 1as illustrated in FIGS. 6 and 7 comprises convolution-type electrodeunits 100 with the lengths and widths sequentially decreasing, such thatthe bare electric roll 10 forms an edge structure similar to a step-likeshape. Still for another example, the electrode assembly 1 asillustrated in FIG. 8, the cathode sheet 100 a and the anode sheet 100 bare arranged in a stacking manner, and the separators 100 c may serve asbarriers sequentially between the adjacent cathode sheet 100 a and theanode sheet 100 b in a folding manner, to form the folding-typeelectrode units.

In addition, when a plurality of electrode units 100 simultaneously areused in one bare electric roll 10, each of the plurality of electrodeunits 100 may select different types according to actual requirements.For example, the electrode assembly 1 as illustrated in FIG. 9 comprisesone lamination-type electrode unit 100 with a smaller width, and oneconvolution-type electrode unit 100 with a greater width. The rightsides of two electrode units 100 are aligned.

In this embodiment, the anti-puncture cushion 12 may be divided intomultiple sections, for example, an upper section, and a lower section,or several sections in a parallel arrangement along the thicknessdirection; wherein each section of the anti-puncture cushion 12 isseparately adhered on two sides along the width direction of the bareelectric roll. Or, each section of the anti-puncture cushion 12 isdirectly adhered on two sides along the width direction of the bareelectric roll 1, and completely warps the two sides of the bare electricroll 10. In this manner, the anode sheet 100 b and the rib structure 100d may be all covered together, and compared with the multi-sectionprocess, this process is simple and easy to operate. A viscous tape maybe directly selected for the anti-puncture cushion 12. For example, abi-axially oriented polypropylene (BOPP) tape which is commonly used onthe lithium ion battery is selected, for example, a green glue commonlyknown.

The probability that the laminated aluminum film 2 is punctured by theanode current collector of the anode sheet is significantly reduced bythe lithium ion electric roll according to this embodiment.

The technical solutions provided in the present application may achievethe following beneficial effects:

A lithium ion electric roll according to the present application iscapable of increasing a layer of protection isolation structure betweenan anode current collector and a laminated aluminum film by using ananti-puncture cushion which is arranged on outer side of the anodecurrent collector and is arranged on two sides of a bare electric roll,which significantly lowers the probability of that the laminatedaluminum film is punctured by a pole sheet.

Described above are merely preferred embodiments of the presentapplication, but are not intended to limit the present application. Aperson skilled in the art may derive various modifications andvariations. Any modification, equivalent replacement, or improvementmade without departing from the spirit and principle of the presentapplication should fall within the protection scope of the presentapplication.

What is claimed is:
 1. An electrode assembly, comprising: a firstelectrode unit having a first surface extending along a length directionand a width direction of the first electrode unit, a second surfaceopposite to the first surface, a third surface extending along thelength direction and a thickness direction of the first electrode unit,a fourth surface opposite to the third surface, a top surface extendingalong the width direction and the thickness direction of the firstelectrode unit and a bottom surface opposite to the top surface; a firstanti-puncture cushion; wherein the first electrode unit comprises afirst electrode sheet, a second electrode sheet, and a separator, theseparator is disposed between the first electrode sheet and the secondelectrode sheet; the first anti-puncture cushion is disposed on at leastone of the third surface or the fourth surface along the width directionof the first electrode unit, and covers an edge of the first electrodesheet; the first anti-puncture cushion extends along the thicknessdirection of the first electrode unit and covers a portion of the firstsurface and a portion of the second surface of the first electrode unit,respectively; and the first anti-puncture cushion extends along thelength direction of the first electrode unit and covers a portion of thetop surface of the first electrode unit and a portion of the bottomsurface of the first electrode unit, respectively.
 2. The electrodeassembly according to claim 1, wherein the first anti-puncture cushionis disposed on both the third surface and the fourth surface of thefirst electrode unit along the width direction.
 3. The electrodeassembly according to claim 1, wherein the first electrode sheet is acathode sheet, and the second electrode sheet is an anode sheet.
 4. Theelectrode assembly according to claim 1, wherein an edge of the firstanti-puncture cushion exceeds the second electrode sheet along thelength direction.
 5. The electrode assembly according to claim 1,wherein the electrode assembly comprises a second electrode unit and asecond anti-puncture cushion; the first electrode unit and the secondelectrode unit are sequentially arranged in a stacking manner along thethickness direction; and the second electrode unit comprising a fifthsurface extending along a length direction and a width direction of thesecond electrode unit, a sixth surface opposite to the fifth surface, aseventh surface extending along the length direction and a thicknessdirection of the second electrode unit, an eighth surface opposite tothe seventh surface; the second anti-puncture cushion is disposed on atleast one of the seventh surface or eighth surface.
 6. The electrodeassembly according to claim 5, wherein the first electrode unit and thesecond electrode unit is adjacent, a rib structure is disposed on a sideof the first electrode unit or the second electrode unit; the firstanti-puncture cushion or the second anti-puncture cushion wraps the ribstructure.
 7. The electrode assembly according to claim 5, whereinwidths of the first electrode unit and the second electrode unit aredifferent.
 8. The electrode assembly according to claim 5, wherein thefirst electrode unit and the second electrode unit are partiallystaggered along the width direction.
 9. The electrode assembly accordingto claim 5, wherein the first electrode unit is a lamination-typeelectrode unit; and the second electrode unit is a convolution-typeelectrode unit or a folding-type electrode unit.
 10. The electrodeassembly according to claim 2, wherein the first anti-puncture cushionis adhered on the third surface and the fourth surface of the firstelectrode unit, and completely wraps the first electrode unit along thewidth direction.
 11. The electrode assembly according to claim 10,wherein the first anti-puncture cushion is a tape.
 12. A lithium ionelectric roll, comprising: a laminated aluminum film; and an electrodeassembly, the electrode assembly further comprising: a first electrodeunit having a first surface extending along a length direction and awidth direction of the first electrode unit, a second surface oppositeto the first surface, a third surface extending along the lengthdirection and a thickness direction of the first electrode unit, afourth surface opposite to the third surface, a top surface extendingalong the width direction and the thickness direction of the firstelectrode unit and a bottom surface opposite to the top surface; a firstanti-puncture cushion; wherein the first electrode unit comprises afirst electrode sheet, a second electrode sheet, and a separator, theseparator is disposed between the first electrode sheet and the secondelectrode sheet; the first anti-puncture cushion is disposed on at leastone of the third surface or the fourth surface along the width directionof the first electrode unit, and covers an edge of the first electrodesheet; the first anti-puncture cushion extends along the thicknessdirection of the first electrode unit and covers a portion of the firstsurface and a portion of the second surface of the first electrode unit,respectively; and the first anti-puncture cushion extends along thelength direction of the first electrode unit and covers a portion of thetop surface of the first electrode unit and a portion of the bottomsurface of the first electrode unit, respectively; wherein the electrodeassembly is wrapped by the laminated aluminum film.